1. Technical Field
The present disclosure relates to a vacuum ionization gauge.
2. Description of Related Art
Nowadays, high vacuum conditions are employed in many technological fields, such as simulation technology in aerospace, superconductor technology, nuclear fusion technology, ultra-low temperature technology, and large particle accelerator technology. Vacuum gauges for measuring pressure in ultra-high and extremely high vacuum conditions are needed.
A typical example is shown and discussed in U.S. Pat. No. 7,129,708, entitled, “VACUUM IONIZATION GAUGE WITH HIGH SENSITIVITY” issued to Fan, et al. on Oct. 31, 2006. This patent discloses a vacuum ionization gauge. However, during the use of the vacuum ionization gauge, a high positive voltage needs to be applied to the grid electrode because the field emission array is made of metal, nonmetal, compound, or other nanometer materials which has a relatively poor electron emission characteristic, which will result in the grid electrode attracting the electrons into the shield electrode. The grid electrode catches the electrons in the shield electrode so that the route of the electron in the shield electrode is short. Therefore, the electrons cannot collide with the gas molecules to ionize the gas molecules, and the sensitivity of the vacuum ionization gauge is low.
What is needed, therefore, is a vacuum ionization gauge which has improved sensitivity.